Warehousing operations frequently involve stowage and retrieval of identified platforms or containers, with each platform or container being associated with identified goods placed or packed on the platform or stored in the container. One commonly used platform for stowage and retrieval of goods is a pallet. Identification of each of a plurality of pallets is stored and when goods are loaded onto the pallet, identification of these goods is associated with the stored identification of the pallet. When goods are removed from the pallet, the association of the goods with the pallet is also removed. In this way, tracking of the location of goods is accomplished by tracking of the locations of the pallets onto which the goods are loaded.
Records of locations of pallets are stored in a database. When a pallet is needed, a forklift or other retrieval and transporting device is dispatched to the expected location of the pallet. If the pallet is not in the expected location, a search must be conducted. In typical operations in a warehouse, retrieval and replacement of pallets is continually occurring. Therefore, placement of pallets in incorrect locations, or incorrect recording of locations of pallets, is likely to occur with some frequency so that considerable effort and expense must be devoted to correcting location information for pallets and finding and relocating incorrectly placed pallets. Even if substantial effort is devoted to maintaining proper records of locations of pallets and placing pallets in their proper locations, incorrect storage of pallets and incorrect recording of the locations of pallets is likely to occur.
Warehouse systems frequently employ bar codes to label pallets and locations in which pallets may be placed. Accurate management of pallet location information in such a system typically requires that a pallet label and a location label be scanned whenever a pallet is placed, retrieved, moved, or replaced. If scanning is neglected, or if a scan fails to read a pallet's bar code without the failure being noticed, location information will be incorrect. In addition, bar code systems do not in and of themselves provide easy and convenient notification to an operator when the operator is approaching a location from which a pallet is to be retrieved or to which a pallet is to be restored, and they do not serve to guide an operator to a location.